1. Field of the Invention
The present invention relates to a disk reproducing apparatus for reproducing a disk, which is a disc-shaped recording medium, and more particularly to the disk reproducing apparatus for reproducing a CD standard disk and a DVD standard disk and a disk type identifying method.
2. Description of the Related Art
With an increase of the variety of disk types, a disk reproducing apparatus capable of reproducing a plurality of types of disks has been provided. In the disk reproducing apparatus, different kinds of parameters are employed during a reproducing operation according to the types of the disks. Therefore, the types of the disks to be reproduced must be identified and the parameters must be set according to the identified result. A publication of JP-A-2001-351315 discloses an example of a method for discriminating between a CD standard disk and a DVD standard disk in a system including two lasers each for CD and DVD.
In accordance with the method, as indicated in S7 and S8 in FIG. 3 of the above publication, it is identified whether the disk is a CD standard disk (exclusive of CD-RW) on the basis of a peak/peak value (CDFEpp) of a focusing error signal when a focus searching is being performed by turning on a CD laser.
Meanwhile, since there are variations in a reflection coefficient of the disk and in a power from the laser, there are also variations in a level of a focus error signal created on the basis of a reflection light from the disk. Therefore, the method disclosed in the publication may erroneously discriminate the type of the disk.
Further, in order to identify the disk type, the method described above requires three values of a peak/peak value of a focusing error signal, a maximum value of the DC component of an RF signal and a maximum value of the AC component of the RF signal. Hence, a problem occurs that the method described above cannot quickly and simply identify the disk type.